Air Canada’s said on Thursday that its load factor, the percentage of available seats filled with paying customers, rose to 83 percent last month from 81.9 percent in the same period last year.

Traffic rose 1 percent despite a 0.3 percent drop in capacity caused by a job action by pilots and maintenance rescheduling required by the shutdown in March of Air Canada maintenance contractor Aveos Fleet Performance.

WestJet Airlines Ltd, Canada’s second-biggest airline, said its load factor rose to 86.2 percent in April from 83.6 percent a year earlier. Traffic rose 8.2 percent, while capacity was up 5 percent over the same period.

The airline, which this week said it will buy up to 45 planes from Bombardier for a regional carrier it will launch late next year, flew 1.48 million passengers in April, a gain of more than 120,000 from last year.

“The demand environment remains strong and we are optimistic that this positive momentum will continue throughout 2012,” Chief Executive Gregg Saretsky said in a statement.

Privately owned short-haul airline Porter had a record load factor of 62.1 percent in April, up from 54.1 percent a year earlier. Traffic jumped 40.5 percent, while capacity rose 22 percent.

“Our recent launch in Washington received the highest advance sales of any of our U.S. destinations, contributing to our strong April load factor,” said Chief Executive Robert Deluce.